Image imported from derpibooru 
Original Description:
 
If you want to win it all, you have to risk it all, and that extends to the world of placing bets. Rainbow Dash, on the verge of her biggest, baddest stunt ever (doing five sonic rainbooms in a row), overheard several of her friends taking bets on if she could pull it off. Amused that there was every any doubt about her abilities, she made them all an offer: If she failed to pull off the greatest stunt Equestria had ever seen, she would submit to doing whatever everyone wanted to do to her for three days. But if she won, all of them would have to do what she wanted for three days.
 
Thinking that the most famous flyer in Equestria had pushed herself too far, her friends decided to take her up on her bet. And as Dash spread her wings and headed off to do the impossible, they were already smirking at all the things they could do with Dash when she came to pay up on her failure.
 
To their shock, five sonic rainbooms filled the sky moments later.
 
An hour later, after all the congratulations were finished, Dash walked over to her friends with the biggest smirk on her face. Everyone figured they’d have to clean her house, do some home improvement project, or something similar, and in a way, they were right: Having redone her bedroom, Dash was temporarily without a bed.
 
Oh, so you want us all to make you the most ornate bed possible?
 
Nope, Dash said. Got one on order. But it won’t arrive for a while. So until then, all of you will be my bed!
 
When everyone realized what Dash meant, they were stunned. But a bet was a bet, and they had lost, so at the appointed hour, they came to Dash’s home, lined up, and submitted themselves to her.
 
One after another, Dash strapped each of her friends inside a Securu Sack, locked it down tight, and laid them across her old, empty bedframe one after the other. When everyone was in place, she strapped them down to keep them from rolling out onto the floor, stepped back, and admired her handiwork as her friends squirmed and tested their bonds. She had the most unique, one-of-a-kind bed in all of Equestria! And as per the terms of the bet, her friends would come over for three nights to serve as her mattress until her new bed arrived.
 
Dressing herself in her favorite rubber suit, Dash carefully crawled onto her friends, lay down, and cuddled Soarin’, who had the privilege of being her bodypillow for the night. Exhausted as she was, it wasn’t long until Dash was out cold, leaving everyone else to come to terms with the fact that they had been turned into furniture. Thankfully, Dash wasn’t too heavy, so it wasn’t uncomfortable having her lie on them, but most of them wouldn’t get much sleep, save Twilight, who had done this sort of thing many times before with Princess Celestia was used to it and could easily sleep while bound. And with three nights of this arrangement, the others would have plenty of time to get accustomed to it as well… and maybe come to like it, too.
 

 
This picture (a request by superfun) was my first attempt at fornihilia, something I’m not really into, but after seeing these two pictures, I got inspired to give it ago, as the thought of a bed being formed out of several bound beings was fascinating: sleeping on a living mattress that shifts occasionally under your weight, feeling bound arms and legs squirming every now and then, and hearing the breathing of your living pillows as you snuggle them and rest your head. While the logistics of it would be a nightmare to pull off (not to speak of the numerous safety issues), it’s a fascinating fantasy nonetheless.